Derivative and Other Fair Value Instruments (Details) (USD $)	12 Months Ended
Dec. 31, 2014
Forward Starting Swaps [Member]
Derivative [Line Items]
Current Notional Balance	$ 400,000,000
Lowest Possible Notional	400,000,000
Highest Possible Notional	400,000,000
Lowest Interest Rate	2.274%
Highest Interest Rate	3.191%
Earliest Maturity Date	2025
Latest Maturity Date	2025
Fair Value Hedging [Member]
Derivative [Line Items]
Current Notional Balance	450,000,000
Lowest Possible Notional	450,000,000
Highest Possible Notional	450,000,000
Lowest Interest Rate	2.375%
Highest Interest Rate	2.375%
Earliest Maturity Date	2019
Latest Maturity Date	2019
2.375% Notes [Member]
Derivative [Line Items]
Term Loan Principal Amount	$ 450,000,000
Debt Instrument, Interest Rate, Stated Percentage	2.375%
Term Loan Facility Spread	0.61%

The earliest maturity date on derivatives designated as fair value or cash flow hedging instruments.

No definition available.

Name:	eqr_EarliestMaturityDate
Namespace Prefix:	eqr_
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Highest interest rate on derivatives designated as fair value or cash flow hedging instruments.

+ References

No definition available.

+ Details

Name:	eqr_HighestInterestRate
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Highest possible notional amount of all derivatives designated as fair value or cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds or other units specified in a derivative instrument.

+ References

No definition available.

+ Details

Name:	eqr_HighestPossibleNotional
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The latest maturity date on derivatives designated as fair value or cash flow hedging instruments.

+ References

No definition available.

+ Details

Name:	eqr_LatestMaturityDate
Namespace Prefix:	eqr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Lowest interest rate on derivatives designated as fair value or cash flow hedging instruments.

+ References

No definition available.

+ Details

Name:	eqr_LowestInterestRate
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Lowest possible notional amount of all derivatives designated as fair value or cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds or other units specified in a derivative instrument.

+ References

No definition available.

+ Details

Name:	eqr_LowestPossibleNotional
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Aggregate notional amount of all derivatives designated as fair value or cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

+ References

No definition available.

+ Details

Name:	eqr_NotionalAmountOfHedgeInstruments
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents a spread that is dependent upon a credit rating or bids received from lenders and is blended with an interest rate for amounts borrowed under the term loan.

+ References

No definition available.

+ Details

Name:	eqr_TermLoanFacilitySpread
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the principal amount of the Company's senior unsecured delayed draw term loan facility.

+ References

No definition available.

+ Details

Name:	eqr_TermLoanPrincipalAmount
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DerivativeByNatureAxis=eqr_ForwardStartingSwapsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeByNatureAxis=us-gaap_FairValueHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=eqr_A2.375NotesMember
Namespace Prefix:
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Period Type: